add phaser cmd

doc/README.md

@@ -23,6 +23,8 @@ where in the file you want the plugin to be ran.
 so, if you did `plugin 3 1...`, it would split the file in 3, then get the
 part that is of index 1 (starting at 0).
 
+**Keep in mind parts start from the bottom of the file.**
+
 ## `load path_or_arg`
 
 Load a file into memory. The file MUST end with the bmp extension (and so MUST
@@ -46,6 +48,17 @@ Run the DJ EQ plugin from the SWH plugins.
 `lo`, `mid`, and `hi` are the respective dB gains for each frequency range.
 
 All three ranges accept gains from -70dB to +6dB.
+Default is 0 for all (no action taken).
+
+## `phaser split index lfo_rate lfo_depth fb spread`
+
+Run the LFO Phaser plugin from the SWH plugins.
+
+Parameters:
+ - `lfo_rate`: LFO Rate (Hz), 0..100, default 25
+ - `lfo_depth`: LFO depth, 0..1, default 0.25
+ - `fb`: Feedback, -1..1, default 0
+ - `spread`: Spread (octaves), 0..2, default 1
 
 ## TODO `echo split index delay`